Japanese Patent Application Publication No. 2005-156455 to TETSUYASU-et-al. is representative of an optical fiber unit in this art (see optical fiber unit 10). FIG. 49 is a perspective view of the described optical fiber unit. FIG. 50 is a perspective exploded view of the optical fiber unit 10.
As shown in FIG. 50, the optical fiber unit 10 described by TETSUYASU-et-al. includes head 11, cover 12, and nut 13. The head 11 includes a cylindrical portion 14 and an optical fiber holder 17. The cylindrical portion 14 includes a through-hole 18, in which an optical fiber cable 15 is inserted. The optical fiber holder 17 includes a groove 22, which communicates with the through-hole 18. The optical fiber holder 17 is shaped in a hexagonal prism defining the groove 22. The optical fiber holder 17 has an opening 23 in one side of its periphery. The optical fiber cable 15 is inserted in the through-hole 18 of the cylindrical portion 14 and in the groove 22 of the optical fiber holder 17, bent at a predetermined curvature and then extends from the opening 23.